Rotary compressor



Feb, W, H96? 3, M. sc 3,302,870

ROTARY COMPRES SOR Filed Feb. 25, 1966 2Q INVENTOR.

/24 6 M. swam United States Patent 3,302,870 ROTARY COMPRESSOR Carl M. Schell, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Feb. 25, 1966, Ser. No. 530,089 Claims. (Cl. 230-449) This invention relates to rotary compressors and more particularly to reversible rotary compressors suitable for association with reverse gas' cycle defrosting systems in refrigerators or the like.

In certain refrigerant systems and the like, it is desirable to include a compressor in the system for discharging hot gas into a condenser, thence through a refrigerant expansion device such as a capillary tube and through an evaporator from" whence refrigerant gas is directed into the compressor during a compression phase of operation thereof. Such compressors in certain cases desirably are reversible so that the gas flow through the refrigerant system is reversed periodically to defrost the evaporator unit therein.

An object of the present invention, therefore, is to improve rotary compressors for association with reverse gas cycle refrigeration defrosting systems by the provision of an elliptical rotor operatively associated with oscillating rocker members having spaced apart arms cooperating with the elliptical rotor to form a plurality of variable volume pumping chambers in a pumping mechanism enclosure formed by end plates-that seal the ends of the variable volume chambers formed by the elliptical rotor and the oscillatable rocker members and wherein the elliptical rotor and rocker members cooperate to produce two compression strokes in each of the pluralities of variable volume pumping chambers during one rotation of the elliptical rotor to produce a high volumetric efiiciency in the assembly.

A further object of the present invention is to improve rotary compressors of the type including an elliptical rotor by the provision of a low-cost pump mechanism enclosure including spaced apart end plates closing the ends of spaced apart variable volume chambers within the pump mechanism enclosure formed solely by the elliptical rotor and a pair of oppositely located rocker members each having spaced apart arms engaging the outer periphery of the elliptical rotor and oscillatable with respect to the rotor upon rotation thereof to produce two compression strokes during each rotation of the elliptical rotor within the pump mechanism enclosure.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings FIGURE l'is a top elevational view of the improved compressor of the present invention with one end plate thereof removed, showing one phase of the operation thereof;

FIGURE 2 is a view like FIGURE 1 showing the operative parts of the compressor assembly in a second operative position;

FIGURE 3 is a view in vertical section taken along the line 3-3 of FIGURE 1 with the end plate in place and with the compressor shown in association with a diagrammatically illustrated refrigeration system that is defrosted periodically by reversely rotating the cornpressor;

FIGURE 4 is a fragmentary, vertical sectional view showing a modification of the details of the outlet from the variable volume pumping chambers of the compressor; and

FIGURE 5 is a fragmentary, vertical, sectional view Fatented Feb. 7, 1967 of a modification ofthe inlet to the compressor of FIG- URES 1 through 3.

Referring now more particularly to the drawings, an improved plural chamber compressor 10 constructed in accordance with the principles of the present invention is representatively illustrated in association with a refrig' erant system including conduits 12, 14 that are joined at 16 to direct refrigerant through a condenser 18. The condenser 18 is connected through an elongated capillary tube 20 which directs refrigerant to an evaporator unit 22 for cooling :1 refrigerated space. The outlet of the evaporator unit 22 is connected by a conduit 24 which branches at 26 and 28 with the branches 26, 28 being connected, respectively, to fluid fittings 30, 32 to the compressor 10. i

In systems of the illustrated type, periodically it is desirable to defrost the evaporator unit 22 for removing frost buildup thereon. .:'17he compressor 10 has certain characteristics-that enable it to be operated in reverse directions whereby fluid is directed through both the conduits 12, '14 through the condenser and thence returned from the evaporator 22 back to the compressor through the-conduits 26, 28. This constitutes a normal refrigeration cycle of operation wherein the evaporator 22 operates to cool a space located in heat transfer relationship therewith, for example, a food storage compartment in a refrigerator. When the compressor 10 is operated in a reverse manner, hot refrigerant gases are discharged therefrom through the conduits 26, 28 and passed in a reverse direction through the evaporator coil 22, the expansion capillary tube 20 and thence through the condenser 18 to be returned to the compressor 10 through the conduits 12 and 14. Such operation constitutes a well-known reverse cycle gas defrost operation in the system.

Referring now more particularly to the compressor 10, in FIGURES lthrough 3, it is illustrated as including a first end plate 34 having a generally hexagonal shape as shown in FIGURES 1 and 2. On the end plate 34 is located a separator plate 36 that bounds a pump mechanism enclosure 4t). The enclosure 4-0 is closed at one end thereof by the end plate 34 and at the opposite end thereof by a second plate 42 that. has a central outwardly directed bearing hub 44 thereon in which is located a sleeve bearing 45 that rotatably supports a drive shaft 4-8 journalled withint'he bearing hub 44 and directed outwardly thereof. The opposite end of theshaft 48 is connected to an elliptical rotor 5th which has a guide shaft 52 connected'thereto directed through a bearing hub 54 on the end plate 34. The elliptical rotor 50 thereby is axially guided and driven by the shaft 48 for rotation between the end plates 34, 42 within the pump mechanism enclosure 40.

In accordance with certain principles of the present invention, the spacer plate 36 itself forms no part of the pressurized pumping chambers in the compressor 10. Rather, inthe illustrated arrangement, a pair of spaced apart oscillatable rocker members 56, 58 are located in the pump mechanism enclosure 40 formed by the'end plates 34, 42 and the spacer plate 36 on either side of the elliptical rotor 50 as best seen in FIGURE 1. The rocker member 56 has a centralsegment 60 thereof pivotally secured to the end plates 34,42 by a pivot pin 62 directed therethrough. From the central portion 60 of the rocker member 5a are directed elongated arms 64, 66 that are located in engagement with the outer periphery of the elliptical rotor 50 to form a variable volume pressurizable pumping cavity 68 there-between. Likewise, the rocker member 58 \has a central portion 70 thereof pivotally secured to the end plates 34, 42 by a pivot pin 72. From the central portion 70 is directed a pairof spaced apart arms 74, 76 that also engage the outer periphery of the elliptical rotor to form a second variable volume pressurizable pumping cavity 78 on the opposite side of the rotor 50 from the cavity 68. The pumping chambers 68, 78 are closed at their ends by the end plates 34, 42 which are interconnected by suitable fastening means shown as screws 80, located at spaced apart points along the outer periphery of the end plates 34, 42 and being directed through the separator plate 36 into threaded engagement with the end plate 34. The end plate 34 also includes a plurality of relatively large diameter openings 82, 84 therein which communicate, respectively. with the pumping cavity 68 and pumping cavity 78. The fluid fittings 30, 32 fluidly connect the openings 84, 82 with the conduits 26, 28 of the illustrated refrigerant system or a like system in which the compressor is operated. Additionally, in the end plate 34 are located smaller diameter openings 86, 88 at spaced apart points in the end plate 34 on diametrically opposite sides of the rotor 50 which communicate with the conduits 12, 14 through suitable fitting means (not shown) so as to be connected to the illustrated refrigerated system. In the illustrated arrangement, at the openings 86, 88, the end plate 34 is recessed at 90.

By virtue of the illustrated arrangement, when the shaft 48 is driven to rotate the elliptical rotor 50, it coacts with the rocker members 56, 58 which oscillate about the pivot points defined by the pins 62, 72 to produce two compression strokes from the pumping chambers 68, 78 during each revolution of the rotor 50. More particularly, in the operative position shown in FIGURE 1, the rotor 50 on clockwise rotation causes the rocker members 56, 58 to pivot in a direction to cause the variable volume pumping chambers 68, 78 to become reduced in size whereby refrigerant gas or the like therein is compressed and discharged through the openings 86, 88 into the conduits 12, 14 from whence they are directed through the condenser 18, the capillary tube and the evaporator 22 which is cooled by the refrigerant expanded by the tube to lower the temperature of an associated food storage compartment or the like. From the evaporator 22 the refrigerant gas passes through the conduit 24 and branch lines 26, 28, thence through the fittings 30, 32 and the openings 84, 82 which are opened following the end of the compression stroke as shown in FIGURE 2 into the pumping cavities 68, 78. As the rotor passes from the position shown in FIGURE 2, the rocker arms are progressively pivoted in a direction to cause the variable volume pumping cavities 68, 78 to increase in size where by the return gases are drawn into the pumping cavities to produce a suction or inlet phase as the rotor 50 is moved from the position shown in FIGURE 2 through the completion of the discharge stroke to a position 180 offset from that shown in FIGURE 1 about the axis defined by the shaft 48. Following the compression stroke the rotor 50 is driven another 90 to complete a second compression stroke during its first revolution and subsequent to the second compression stroke, the rocker members 56, 58 are pivoted about the pins 62, 72 by the rotor 50 as it returns to its original position through a second inlet or suction stroke during the first revolution of the rotor 50.

The particularly illustrated arrangement of the rocker arms 56, 58 on either side of the rotor 58 serves in cooperation with the outer periphery of the rotor to form the sole means bounding the peripheral extent of the pumping cavities 68, 78 and the arrangement affords an unusually balanced force distribution on the rotor 58 whereby wear in the assembly is evenly distributed on the operative parts of the assembly represented by the rotor 50, the rocker member 56 and the rocker member 58.

Upon a reverse rotation of the rotor 50, the compressor 10 will cause fluid to be drawn through the openings 86, 88 and discharge the fluid through the openings 82, 84 whereby hot compressed gas will be passed through the conduits 26, 28 and conduit 24 into the evaporator 22 for raising the temperature thereof sufliciently to remove frost buildup therefrom. From the evaporator 22 the refrigerant is passed to the capillary tube 20 and the condenser 18 and is returned through the conduits 12, 14 into the pumping chambers through openings 86, 88. For example, in the position shown in FIGURE 1, the rotor 50, when driven in a counterclockwise direction, will first block the openings 86, 88 and thereafter dis-charge fluid from the pumping cavities 68, 78 through the openings 82, 84. Following the compression stroke in the initial counterclockwise rotation of the rotor 50, as shown in FIGURE 2, the ports 86, 88 are open to the pumping cavity and return refrigerant will be passed therethrough into the cavities 68, 78 during an inlet or suction stroke of the rotor 50, which takes place as the space between the rocker members 56 and 58 and the rotor 50 is increasing.

If desired, under certain other uses, the compressor 10 can have valving associated therewith for controlling fluid flow into the pumping cavities 68, 78. One example of such valving is shown in FIGURE 4 where an opening 86' (like either opening 86 or 88 in the embodiment of FIG- URES 1-3) in an end plate 34 is illustrated as having an elongated spring member 92 or reed valve overlying the port 86 having one end thereof fixedly secured to the end plate 34 by suitable means such as a rivet 94 and the opposite end thereof free to move with respect to the end plate 34 to prevent fluid flow through the opening 86' into the pumping cavity but allowing fluid flow through the opening exteriorly of the pumping cavity. In this case, the opening 86 constitutes a discharge opening and the compressor is operative in the illustrated unit only when the rotor 50 is driven in a clockwise direction. The openings 82, 84 in the end plate 34, where valving is desired, may be associated with one-way inlet valve assemblies, for example, of the type shown in FIGURE 5 which shows an opening 82 (like either opening 82 or 34 in the first embodiment) axially aligned with a valving element 96 resiliently biased by a spring member 98 in an opening 100 in an end plate 101 (like end plate 34 in FIGURES 1-3) against a valve seat 102 formed on the inner end of a fluid fitting 103 which has a flange 104 thereon secured to the end plate 101 by suitable fastening means shown as screws 105. By virtue of this arrangement, the valving element 96 prevents fluid flow from the compressor through the opening 82' and only allows fluid fiow interiorly of the compressor through these openings, whereby they constitute suction or inlet valves in a modified pump assembly.

In view of the description of the illustrated embodiment of the invention, it will be appreciated by those skilled in the art that the applicant has developed a novel, plural pumping cavity rotary compressor assembly that is unusually balanced an consisting of a small number of parts that are easily assembled to form an operative compressor arrangement. Moreover, by the virtue of the relative simplicity of the construction, it is readily suited for association with various types of operative systems, such as a refrigerant arrangement wherein the compressor can be reversely driven to produce a cooling cycle of operation in the refrigerant system or to produce defrosting of an evaporator in the system as desired. The construction, furthermore, can be readily modified to include suitable valving locatable on only one end plate of the compressor, if desired, to produce a unidirectional flow of fluid therethrough as the pump is operated in a continuous direction.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A plural pumping chamber compressor comprising, a first end plate, a second end plate, means supporting said first and second end plates in spaced relationship to form a pump mechanism enclosure therebetween, a first oscillatable rocker member located between first, and

second plates in engagement therewith for sliding movement relative thereto, a second oscillatable rocker member located between said first and second plates at a point Within said pump mechanism enclosure spaced from said first rocker member and in engagement with said first and second end plates for slidable movement relative thereto, each of said first and second rocker members having spaced apart arms joined at a juncture point, an elliptical rotor located within said pump mechansm enclosure between said first and second rocker members having an outer peripheral surface thereon continuously engaging said spaced apart arms of each of said first and second rocker members, said rotor having an axis of rotation located on a straight line between said rocker member juncture points, means for pivotally mounting each of said rocker members at the juncture thereon be tween said spaced apart arms thereof to at least one of said end plates, said elliptical rotor and said spaced apart arms forming a pair of spaced apart diametrically opposite variable volume pumping chambers on the outer periphery of said rotor bounded on their peripheries solely by said rotor and said rocker arm members for balancing the fluid pressure force acting on said rotor, said end plates sealing the ends of said variable volume chambers, means forming an inlet and an outlet to each of said spaced variable volume chambers, means for rotating said rotor, said rotating elliptical rotor engaging said spaced apart arms of each of said rocker members causing said rocker members to oscillate about their pivot points, said oscillating rocker arms each cooperating with said elliptical rotor to concurrently draw fluid from said inlet and thence to discharge fluid through said outlet lets and outlets to said variable volume pumping chambers.

3. In the combination of claim 1, said inlet means and said outlet means including openings formed in one of said end plates, said openings for said inlets serving as discharge openings upon a predetermined rotation of said rotor and said openings for said inlet to said pumping chamber serving as an outlet during said predetermined rotation of said rotor.

4. In the combination of claim 1, said means for rotating said elliptical rotor including a shaft directed through one of said end plates and being iourn-alled in said end plate for rotation with respect thereto, said inlet and outlet means to said variable volume pumping chambers including a first pair of spaced apart openings located in the other of said end plates and a second pair of spaced apart openings located in the other of said end plates.

5. in the combination of claim 1, said means for directing fluid into said variable volume pumping chambers including a pair of spaced apart openings in one of said end plates, and valve members in said end plates for blocking fluid flow out of said inlet openings, said means for discharging fluid from said pumping chambers including a second pair of spaced apart openings in said one of said end plates, and valve means on said one of said end plates for blocking fluid flow through said outlet openings interior ly of said pumping chambers.

References Cited by the Examiner UNITED STATES PATENTS 1,972,302 9/1934 Hutchison 103-124 2,084,846 6/1937 Hutchison 103-124 3,186,385 6/1965 Walker 123-15 FOREIGN PATENTS 930,280 7/1963 Great Britain. 1,006,408 9/ 1965 Great Britain.

DONLEY J. STOCKING, Primary Examiner. WELBUR I. GOODLIN, Examiner. 

1. A PLURAL PUMPING CHAMBER COMPRESSOR COMPRISING, A FIRST END PLATE, A SECOND END PLATE, MEANS SUPPORTING SAID FIRST AND SECOND END PLATES IN SPACED RELATIONSHIP TO FORM A PUMP MECHANISM ENCLOSURE THEREBETWEEN, A FIRST OSCILLATABLE ROCKER MEMBER LOCATED BETWEEN FIRST AND SECOND PLATES IN ENGAGEMENT THEREWITH FOR SLIDING MOVEMENT RELATIVE THERETO, A SECOND OSCILLATABLE ROCKER MEMBER LOCATED BETWEEN SAID FIRST AND SECOND PLATES AT A POINT WITHIN SAID PUMP MECHANISM ENCLOSURE SPACED FROM SAID FIRST ROCKER MEMBER AND IN ENGAGEMENT WITH SAID FIRST AND SECOND END PLATES FOR SLIDABLE MOVEMENT RELATIVE THERETO, EACH OF SAID FIRST AND SECOND ROCKER MEMBERS HAVING SPACED APART ARMS JOINED AT A JUNCTURE POINT, AN ELLIPTICAL ROTOR LOCATED WITHIN SAID PUMP MECHANISM ENCLOSURE BETWEEN SAID FIRST AND SECOND ROCKER MEMBERS HAVING AN OUTER PERIPHERAL SURFACE THEREON CONTINUOUSLY ENGAGING SAID SPACED APART ARMS OF EACH OF SAID FIRST AND SECOND ROCKER MEMBERS, SAID ROTOR HAVING AN AXIS OF ROTATION LOCATED ON A STRAIGHT LINE BETWEEN SAID ROCKER MEMBER JUNCTURE POINTS, MEANS FOR PIVOTALLY MOUNTING EACH OF SAID ROCKER MEMBERS AT THE JUNCTURE THEREON BE- 